What are you expecting them to do, go get Max and Piastri? Of course they are building a bad team right now, because they do not have the reputation to get the best drivers in the world. Plus, this is going to be their first year, and while they are willing to spend a ton of money on this, they need to make sure they spend carefully, they can't just go get 2 drivers with 40 million salary or something, they just need to keep it low.
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Actually, it's not all that bad, because Bottas, Perez, and Mick aren't new to F1. All three drivers have been in F1 before. Even if they haven't shown flashy performances, Perez and Bottas have years of experience in F1, and that would be the best input for Cadillac in building their team. As for Mick, he's Michael Schumacher's son, and Cadillac considers the economic value he brings to the team. Mick has also demonstrated his seriousness in improving if given the opportunity to drive for Cadillac.
The most sensible driver lineup, in my opinion, is Perez and Mick, with Bottas serving as their reserve driver.